1. Field of the Invention
The present invention relates to a method of preventing toner from scattering off a photosensitive member in an electrostatic or electrophotographic copying machine.
2. Description of the Prior Art
Known electrostatic or electrophotographic copying machines include a corona discharger for charging a photosensitive member, the corona discharger having a shield case which is grounded. When the copying machine is in a mode of operation in which an image is being formed, a mass of toner is prevented by a blade member held in sliding contact with the photosensitive member from reaching a development unit as the photosensitive member moves. During a mode of operation in which no image is being formed, the blade member is lifted off the photosensitive member. The toner which is charged positively or negatively now tends to float off the photosensitive member and stick to the shield cases of the corona dischargers. Where the developer is composed of toner and carrier (two-component developer), the toner is light in weight, and liable to scatter around and to smear surrounding parts. One solution would be to incorporate a fan for exhausting toner-laden air, thereby protecting the parts against toner contamination. However, such an attempt would render the overall apparatus excessively complicated.
It is an object of the present invention to provide a method of preventing toner from scattering off a photosensitive member and hence from smearing parts surrounding the photosensitive member when the toner is conveyed to a development unit by the photosensitive member during a mode of operation in which no image is being formed on the photosensitive member.